The invention relates to dry powder inhalation apparatus. This apparatus administers a dry powder medicament in a desired predetermined dose to a user of the apparatus who actuates the apparatus manually and then breathe in the predetermined dose, or, on taking a breath, would automatically actuate the device for breathing in the predetermined dose of medicament. Breath actuation is typically used to dispense the desired dose of medicament into the lungs of the patient. The medicament is carried in air during inhalation so that fine particles are carried into the lungs and heavier particles are retained in the buccal cavity.
Typically such an apparatus includes a reservoir for containing the medicament in dry powdered form. The reservoir contains medicament for a particular number of doses. The doses are metered from the reservoir one dose at a time on actuation by a user. The apparatus also includes an air inlet or inlets for taking up or entraining the medicament for passage along airways through a mouthpiece of the apparatus and into the lungs of the user when the user takes a breath.
The amounts of medicament in a particular dose are small and received from the reservoir in a device having a receptacle or cup for receiving a metered dose of medicament. The device then shifted bodily in order to transfer the metered dose to the air channels. The body of the device seals off a discharge outlet from the reservoir during this transfer motion.
In known apparatus, a mechanism transfers a slide carrier assembly carrying a metered dose by releasing the slide carrier off the end of a lower ledge of a yoke. A yoke lower moves as a trigger is rotated by a mouthpiece cover opening. The trigger has two drop zones. The first of these is used to generate sudden movement of the yoke lower to compress a bellows for metering. The second drop zone is also sudden, and it is during this zone that the yoke lower releases the slide carrier. The transfer spring forces the slide carrier across a channel between a hopper upper and a hopper lower components. When the slide carrier hits the side wall of the hopper upper the slide carrier stops abruptly.
However, even though a relatively small amount of powder is being dispensed, the powder making up each dose can be compacted which can cause more than the prescribed dosage to be received in the cup.
Moreover, even if there is no compaction, the medicament can be spilled from the cup on transfer. Consequently, although there is a collection well for receiving spilled medicament, the required desired dosage may not be administered when the user takes a breath.
Both disadvantages of compaction and spillage result from the way in which the device is transferred from the discharge outlet of the reservoir to the position for passage of the medicament into the air channels.
Accordingly, the present invention mitigates these disadvantages.